We have continued our evaluation of an arginine-restricted diet as experimental therapy in gyrate atrophy. We have 13 patients on diet. Four of these have had good biochemical control and stabilization of their chorioretinal degeneration indicating that systemic biochemical correction is beneficial. Additional, we have identified ten different mutations in the OAT enzyme in patients followed here and we are beginning to correlate the nature of these mutations to the clinical and metabolic phenotype.